An Aerosol-Generating Substrate for Vaping Comprising Semi-Solid Substrate

ABSTRACT

An aerosol-generating substrate for vaping includes a semi-solid substrate, wherein up to about 1.0% of the total weight percentage of the aerosol-generating substrate is comprised of one or more carboxylic acids dissolved in an alcohol solution. A method of manufacturing the aerosol-generating substrate and a use thereof in an aerosol-generating substrate for vaping are also provided.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to an aerosol-generating substrate and its manufacturing method. The invention also relates to an aerosol-generating article comprising the aerosol-generating substrate.

BACKGROUND OF THE INVENTION

Recently different kinds of aerosol-generating articles and its devices for use as a new form of smoking have been mushrooming and commercially available on the market. These include one of the most well-known new form of e-cigarettes (vaping) that are electrically heated in which an aerosol is generated by the transfer of heat from a heating element of the aerosol-generating device to the aerosol-generating substrates or materials.

It has been reported that in heat-not-burn aerosol-generating articles, aerosol-forming substrate is heated at a rather relatively low temperature, for instance below 350° C., to avoid combustion thereof. A charge of inhalable aerosol can then be released from the aerosol-generating article. The aerosol released is originated from the aerosol formers, which are incorporated into the tobacco material, which may be particulated or granulated.

Some of the tobacco blends, especially those provided in form of e-juice often triggers coughing (also known as coughing fit) during vaping. One of the reasons contributing to such coughing fit probably due to the fact that e-cigarettes have a very different method of inhalation compared to most tobacco smokers. Some irritants present in the e-liquid may also contribute to the coughing fit.

It would therefore be desirable to provide a solution to overcome the above-mentioned problems as well as to provide an alternative which is capable of delivering a more pleasant smoking and/or vaping experience.

In a further aspect, it is also the aim of the present invention to provide a solution for improving the sensory properties of the above-mentioned consumables.

SUMMARY OF THE INVENTION

The inventors of the present invention have found solutions to the above-discussed problems through the aerosol-generating substrate for the aerosol-generating article.

A first aspect of the invention is accordingly to provide an aerosol-generating substrate for vaping, comprising semi-solid substrates, wherein up to about 1.0 wt. % of the total weight percentage of the aerosol-generating substrate are comprised of a carboxylic acid-containing alcohol solution, wherein one or more carboxylic acids are dissolved in the alcohol solution, wherein the semi-solid substrate is provided in form of a foam.

A second aspect of the invention is accordingly to provide a method of preparing an aerosol-generating substrate for vaping, comprising a semi-solid substrate in form of a foam, comprising the steps of:

a. Providing an aerosol-generating substrate comprising one or more components selected from the list consisting of propylene glycol, 1, 3-Propanediol, glycerol and water;

b. Providing one or more carboxylic acids to an alcohol solution, followed by incorporating the one or more carboxylic acid-containing alcohol solution to the aerosol-generating substrate to form a mixture, such that up to about 1 wt. % of the total weight percentage of the aerosol-generating substrate are comprised of the one or more carboxylic acids-containing alcohol solution;

c. Optionally adding one or more components selected from the list consisting of gum, nicotine, flavourant and binder into the mixture;

d. Constantly mixing the mixture for a certain amount of time, and heating the mixture slightly above room temperature, thus creating semi-solid substrate in form of a foam.

A third aspect of the invention is to provide an aerosol-generating substrate according to the present invention for use in reducing coughing fit from vaping.

A fourth aspect of the invention is to provide an aerosol-generating substrate obtainable according to the present invention.

The inventors have found out that the aerosol-generating substrate according to the present invention, thanks to the small amount of carboxylic acids dissolved in an alcohol solution (wherein up to 1.0 wt.-% of the total weight percentage of the aerosol-generating substrate are comprised of the one or more carboxylic acids-containing alcohol solution), wherein the aerosol-generating substrate comprising semi-solid substrate provided in form of a foam or tobacco mousse), the aerosol-generating substrate according to the present invention unexpectedly reduces the coughing fit to an acceptable level. Moreover, it was found out also that the taste becomes smooth without any negative off taste. This effect of reducing coughing fit is particularly noticeable when one or more carboxylic acids such as stearic acid and/or decanoic acid are present in the alcohol solution of aerosol-generating substrate.

According to some embodiments, the aerosol-generating substrate comprises between 0.2 wt. % and 1 wt. % of the carboxylic acid-containing alcohol solution based on the total weight percentage of the aerosol-generating substrate, preferably about 0.2 wt. %, 0.5 wt. %, 0.8 wt. %, or 1.0 wt. % of the carboxylic acid-containing alcohol solution in the total weight percentage of the aerosol-generating substrate. These ranges or amounts of the carboxylic acid present in the mixture are sufficient to reduce the irritation of throat/coughing fit to an acceptable level.

According to some embodiments, the carboxylic acid-containing alcohol solution is provided in a concentration of between about 0.05 v/v % and about 0.2 v/v %, preferably between 0.08 v/v % and 0.15 v/v %, or more preferably at 0.1 v/v %. The concentration used herein are provided in volume percent concentration for instance (v/v %), molarity or may be provided in mass percent concentration.

According to some embodiments, the carboxylic acid has a hydrocarbon chain length between 9 and 30 carbons, preferably between 10 and 20 carbons.

According to some embodiments, the carboxylic acid is selected from the list consisting of Benzoic acid, Levulinic acid, D/L-Tartaric acid, Capric acid, Pyruvic acid, Citric acid, Fumaric acid, D/L-Lactic acid, D/L-Malic acid, Sorbic acid, Adipic acid, L-Aspartic acid, L-Glutamic acid, Succinic acid, Gluconic acid, Linoleic acid, Saccharic acid, 3,7 dimethyl-6-octenoic acid, 2-methyl pentanoic acid, trans-2-Hexenoic acid, Caprylic acid, Lauric acid, Stearic acid, Butyric acid, Linolenic acid, Malonic acid, Myristic acid, Oleic acid, Palmitic acid, Phenylacetic acid, Propionic acid, Valeric acid, Decanoic acid, Hexanoic acid and Octanoic acid.

According to some embodiments, the carboxylic-acid-containing alcohol solution comprises only saturated fatty acid such as stearic acid and/or decanoic acid, preferably in the ratio of 10/90, 20/80, 30/70, 40/60, 50/50 of stearic acid/decanoic acid.

According to some embodiments, the carboxylic-acid-containing alcohol solution comprises only stearic acid or decanoic acid.

According to some embodiments, the alcohol solution comprises only stearic acid and decanoic acid, preferably in the ratio of 10/90, 20/80, 30/70, 40/60, 50/50 of stearic acid/decanoic acid. The inventors have found out that these two compounds are particularly effective in suppressing throat irritations, wherein the ratios of 20/80 to 50/50 of stearic acid/decanoic acid are particularly effective in reducing coughing fit.

According to some embodiments, the aerosol-generating substrate further comprises one or more components selected from the group consisting of propylene glycol, 1, 3 propanediol, glycerol, water, gum, flavourant, additives, nicotine, and binder.

According to some embodiments, the solvent has a pH value in the range from 6 to 7, preferably 6.2 to 6.8, more preferably 6.3 to 6.5. In other embodiments, acidic condition is preferred, for instance between 4 and 6.9.

According to some variants, the carboxylic acid-containing alcohol solution can be prepared for instance by first weighing the weights of the ingredients (e.g. solvent, solute either in solid form or liquid form), mixing the mixture in a bottle, leaving the mixture for at least 24 hours in room temperature for the solute to completely dissolved in the solvent, and finally mixing the mixture before usage in foam making.

According to some embodiments, the mixture is heated at approximately 45° C. and/or aerated or mixed for approximately 5 minutes.

According to other embodiments, the aerosol-generating substrate in form of foam can be prepared for instance by

-   -   Preparing a mixture of aerosol-generating substrate comprising         propylene glycol, glycerine, water and 0.1% carboxylic         acid-containing alcohol solution;     -   Mixing the mixture for 6 minutes at 45° C. (for example with         speed “6” in the Krups machine);     -   Adding gum (preferably within 1 minute) and mix further for 6         minutes at 45° C. (for example with speed “6” in the Krups         machine);     -   Adding tobacco-containing material (preferably within 2 minutes)         and further mix the mixture for 6 minutes at 45° C. (for example         with speed “6” in the Krups machine);     -   Adding a binder (preferably within 1 minute) and further mix the         mixture for 5 minutes at 45° C. (for example with speed “6” in         the Krups machine);     -   Fill the foamed aerosol-generating substrate in molds and heat         in in an oven at about 50 C for about 18 hours.

By “about” or “approximately” in relation to a given numerical value, it is meant to include numerical values within 10% of the specified value. All values given in the present disclosure are to be understood to be complemented by the word “about” unless it is clear to the contrary from the context. In a more limiting condition, the terms are used to include numerical values within 5% of the specified value.

The indefinite article “a” or “an” does not exclude a plurality, thus should be treated broadly.

Unless defined otherwise, technical, and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

A tobacco-containing material can be any compound, mixture, particle matter, and/or solution that contains and/or carries a constituent of tobacco, either artificially included or naturally contained in tobacco, e.g. tobacco, tobacco particles, tobacco flavor and/or nicotine. In contrast, an example for an artificially added non-tobacco-specific flavor would be menthol.

As used herein, the term “aerosol-generating article” refers to an aerosol-generating article for producing an aerosol comprising an aerosol-generating material that is intended to be heated rather than combusted in order to release volatile compounds that can form an aerosol.

As used herein, the term “aerosol-generating substrate” refers to a material, upon heating, capable of releasing volatile compounds, which can form an aerosol. The aerosol generated from aerosol-generating material of aerosol-generating articles described herein may be visible or invisible and may include vapours (for example, fine particles of substances, which are in a gaseous state, that are ordinarily liquid or solid at room temperature) as well as gases and liquid droplets of condensed vapours.

An aerosol-forming agent can be any compound, mixture and/or solution that is capable of forming an aerosol, e.g. when heated and/or in mixture with a tobacco-containing agent. Well known examples include humectants such as glycerin and propylene glycol, other alcohols, such as ethanol, etc.

As used herein, the term “semi-solid substrate” refers to the state of the substrate, which is highly viscous, slightly thicker than semi-fluid. In other words, the semi-solid substrate does not include solid material (i.e. firm and stable in shape) nor liquid or fluid. Examples for “semi-solid substrates” in the present invention are for instance foam, gel, mousse, or thick mucus.

As used herein, the terms “foam” or “mousse” are used interchangeably. In the present case, the foam is referred to elements comprising pockets of air or gas trapped in a liquid or a non-solid material. For example, an open pored foam is to be understood as a foam which can be considered as being formed of a plurality of interconnecting pores (formed out of a structural material derived from the foam forming agent cooperating with the interacting components such as the foam stabilizing agent, solid components such as tobacco particles and some solvent, etc.) which are able to contain fluid, in particular a mixture of humectant/liquid aerosol-forming substrate and air, wherein at least a significant portion (e.g. greater than 50% by volume) of the pores in the foam are fluidly connected with each other, contrary to a closed-cell foam, wherein the majority of the pores form discrete pockets, each completely enclosed by pore-forming material so as to substantially prevent fluid from passing freely between pores. It is currently believed that the mousses formed as described herein are largely open-pored mousses because after cooling or heating of the aerosol-generating material, vapour is released from the mousse, substantially all of the humectant appears to be released based on measuring of the weight of the mousse portion before and after heating, which could not be readily explained if the humectant was not able to travel through neighboring pores to reach the surface of the mousse portion. However, alternative explanations cannot be totally excluded—for example closed pores could perhaps be opened by rupturing a closed cell wall as a result of the pressure of vaporized gas, etc.

An electronic cigarette (e-cigarette) or similar devices like electronic pipes or heat-not-burn devices, as referred to in the present invention, are not particularly limited, and may be used to provide a user with an aerosol to inhale. It can, according to certain embodiments, comprise a mouthpiece, a heater, a receiving portion, e.g. a pod, stick, capsule, and a casing.

As used herein, wt.-% is to be understood as weight percent, based on the total weight percentage of the aerosol-generating substrate, unless explicitly otherwise specified. In the present disclosure, all amounts are given in wt.-%, unless clearly stated otherwise or obvious from context. In the present disclosure, furthermore all amounts given in wt.-% add up to 100 wt.-%. The weight percent are thereby calculated by dividing the mass of each component by the total mass e.g. of the substrate, unless indicated otherwise or clear from context. In the present case, the chemical compounds can also be applied in vol. % accordingly which is within the common capability of a skilled person.

As used herein, vol. % is to be understood as volume percent, based on the total volume of the substrate, unless explicitly otherwise specified. In the present disclosure, all amounts given in vol. % in a particular substrate add up to 100 vol. %. The volume percent are thereby calculated by dividing the volume of each component by the total volume of the substrate, unless indicated otherwise or clear from context.

Similarly, aeration values (also known as pore volumes as used herein) indicate the vol. % of the foam or mousse which is composed of air. The actual aeration values of samples have been estimated using the following procedure: a sample of “foam” is made without taking any action (e.g. whipping or aerating with an aeration machine) to aerate the “foam” and a known volume of this unfoamed “foam”/material is measured. Then a sample of the foam made after performing an aeration step (e.g. a step such as whipping or aerating with an aeration machine) and the same known volume of the aerated foam is again weighed and the percentage reduction in the weight is calculated. By assuming that the aeration of the unfoamed material is zero and by assuming that the air has a negligible weight, this directly gives an estimation of the aeration value by assuming that the reduction in measured weight results from replacement of the unfoamed material with (weightless) air. E.g. if the weight is observed to be 4% less for the same volume of foamed material compared to that volume of unfoamed material, then is assumed that 4% of the unfoamed material has been replaced with air, meaning that the vol. % of air is 4%.

Particle sizes, as disclosed in this invention, can be measured by any suitable method, e.g. sieving or laser diffraction, preferably sieving.

The (dynamic) viscosity described herein refers to the flow behaviour of liquids. It is defined as the internal frictional resistance of a liquid to the application of a pressure or a shearing stress. The dynamic viscosity is given in millipascal-seconds (mPas) and is determined by using a rotary viscometer. The viscosity measured in performed at room temperature i.e. 22° C.

As used herein, “cooling” is to be understood as having a temperature at a room temperature (around 22-24 degrees Celsius) for at least 60 minutes, or at a temperature less than 16° C. for at least 10 minutes, or more preferably at a temperature less than 12° C. for at least 5 minutes.

As used herein, “aeration” is to be understood as introduction of air or gasses into, through an external step, into the material. The aeration can be performed for instance though whipping, beating, mixing, or aerating with an aeration machine such as Krups Prep & Cook HP 5031 mousse whipping shuffle, or by injection air with an aerator, e.g. like Mondomix aerator. Aeration can be carried out at any suitable temperature. The duration of the aeration can be for instance 1, 2, 3, 4, 5 or 10 minutes or more.

DETAILED DESCRIPTION OF THE INVENTION

Present invention relates to an improved aerosol-generating substrate and a method of producing the aerosol-generating substrate thereof. It has been found out that when the aerosol-generating (tobacco-containing) substrate of the present invention comprises up to 1.0 wt. % carboxylic acid (which is dissolved in a alcohol solution) of the total weight percentage of the aerosol-generating substrate, the carboxylic acid-containing aerosol-generating substrate surprisingly reduces throat irritation or coughing fit.

Vaper's cough is a condition not uncommon among vapers especially those who are new in e-vaping. Inhaling the vapour sometimes triggers a nasty coughing fit i.e. irritation causing coughing urge upon inhalation of an aerosol generated by heating of the substrate. There could be multiple factors for triggering such a coughing fit. For instance, some vapers are affected by the unadulterated nicotine in e-cigarettes, or the coughing may be triggered by inhaling too deeply, or too quickly, or the vaporizer's advanced settings are not fine-tuned accordingly.

While a certain throat irritation is welcome for a tobacco-based aerosol (as it is closer to the so-called “throat kick” sought after by cigarette smokers but not observed with e-cigarette aerosols), it is however necessary to control the irritation sensation caused by the aerosol to avoid actual coughing urge during consumption of a e-vaping material such as a tobacco mousse substrate.

In the present case, the inventors have investigated the possible alternative formulas of an aerosol-generating substrate which are particularly aimed at reducing coughing fit. The inventors found out that when up to about 1.0% of the total weight percentage of the aerosol-generating substrates are comprised of the one or more carboxylic acid in an alcoholic solution, the surprising effect of coughing fit reduction (or reduction of throat irritation) has been observed.

It is furthermore disclosed herein that the reduction of the coughing fit was particularly obvious when the aerosol-generating substrate comprises semi-solid substrate e.g. that the aerosol-generating substrate is provided in form of semi-solid substrate such as foam or mousse form or gel form. It is believed that the aerosol-generating substrate comprising carboxylic acid (especially for instance comprising stearic acid and/or decanoic acid), when in semi-solid state i.e. foam or gel, the higher surface to volume ratio allows the carboxylic acid to be vaporised or released more efficiently compared to when the aerosol-generating substrate is provided in a liquid or solid form.

In the present invention, the foam-stabilizing agent may be additionally introduced into the aerosol-generating substrate. The foam-stabilizing agent is not particularly limited as long as it can stabilize the foam to some extent after formation. According to certain embodiments, the foam stabilizing agent of the present foam is selected from the group consisting of cellulose gum, hydroxyalkylated carbohydrates, and mixtures thereof. Both of the cellulose gum and the hydroxyalkylated carbohydrates are not particularly restricted. According to certain, preferred, embodiments, the foam-stabilizing agent is a cellulose gum, particularly a carboxymethylcellulose, or a derivative thereof. An exemplary, preferred, cellulose gum which may be used in the present invention is CEKOL® 2000 and/or Ceroga 4550C (C.E. Roeper GmbH), a purified sodium carboxymethylcellulose each. Another class of suitable foam stabilizing agents are hydroxyalkylated carbohydrates, and more preferably cellulose ethers and derivatives thereof. A cellulose ether or derivative thereof that can be used can have at least one substituent selected from the group consisting of methyl, ethyl, hydroxyethyl and hydroxypropyl groups. It can further be substituted with a linear or branched substituted or unsubstituted alkyl radicals having 1-20 carbon atoms or an aralkyl radical having 7 to 20 carbon atoms. Such radical is preferably attached by an ether linkage. Suitable substituents can e.g. a hydroxy group, a carboxy group with 1 to 4 carbon atoms, etc. According to certain embodiments the cellulose ether is selected from hydroxyethylcellulose, methylcellulose, methylhydroxyethylcellulose, ethylhydroxyethylcellulose, and mixtures thereof. Furthermore, mixtures of different cellulose gums, different hydroxyalkylated carbohydrates, and mixtures of one or more cellulose gum with one or more hydroxyalkylated carbohydrate, as well as derivatives of one or either thereof, can be used. Also included as derivatives are salts of these cellulose ethers, preferably alkali metal salts thereof, e.g. sodium and/or potassium salts thereof.

Similarly, foam-forming agent may be additionally added to the mixture of aerosol-generating substrate. Also, the foam-forming agent is not particularly restricted. According to certain embodiments, the foam-forming agent of the present foam is selected from the group consisting of agar, gellan gum, lecithin, polyglycerol esters of fatty acids, glycerol esters of fatty acids, sorbitan esters of fatty acids, and/or mixtures thereof, without being limited thereto. A preferred foam-forming agent is gellan gum. Glycerol esters can be prepared by standard esterification methods. If glycerol esters of fatty acids are used, the foam-forming agent can suitably be a compound such as glycerol monostearate and/or glycerol monooleate. Polyglycerol esters can be prepared by polymerizing glycerin under alkaline conditions suitably followed by reacting them with specific fatty acids. Suitable polyglycerol esters can be hexaglycerol monooleate, octaglycerol monostearate and/or octaglycerol monooleate. Sorbitan esters of fatty acids used in certain embodiments of the present invention can be sorbitan monostearate, sorbitan monooleate and/or sorbitan mono palmitate. Furthermore, any possible combinations of compounds belonging to the above-mentioned classes can be used.

The present methods can be realized also through by having a step of mixing the aerosol-generating substrate that is aerated after adding of the foam-stabilizing agent and/or after cooling of the mixture. This does not exclude that other aeration steps are also being carried out, and according to certain embodiments, one, two or preferably all of the optional aeration steps are carried out in the present methods. Also, it is not excluded that aeration is carried out already concomitantly with a mixing and/or addition step.

The method of aeration is not particularly restricted and can involve e.g. an injection of air, a whipping in of air—e.g. a mixing with a sufficiently large paddle/shuffle and/or a sufficient paddle movement and/or at sufficient lower speed so that air can be introduced into the mixture, bubbling air through the mixture, etc. For example, aeration can be carried out using a sufficient mixing machine similar to a mixer for preparing a mousse, e.g. a Krups Prep & Cook HP 5031 mousse whipping shuffle, and or by injection air with an aerator, e.g. like Mondomix aerator. Aeration can be carried out at a suitable temperature, e.g. at room temperature (around 20-24° C.), 30-80° C., e.g. to 35-75° C., preferably between and including 30-60° C. In the present methods it is not excluded that aeration is carried out concomitantly with a mixing and/or in a step of adding an ingredient, e.g. when using whipping.

To this end, it is emphasized that the aerosol-generating substrate as claimed presently, even without adding additionally foam-forming agent and/or foam-stabilizing agent, with the above-explained method, the mixture of aerosol-generating substrate can be transformed into semi-solid condition i.e. foam, mousse, gel or the like. In other words, the aerosol-generating substrate of the present invention is a semi-solid substrate.

According to some embodiments of the present invention, ingredients for forming the aerosol-generating foam such as the aerosol-forming agent, the form-foaming agent, the foam-stabilizing agent, the tobacco-containing agent, the inhalable agent, the at least one non-tobacco flavoring agent and the solvent are not particularly restricted. Also, a gas used for aeration is not particularly restricted, and can be e.g. air. Also, further components can be admixed. According to certain embodiments, essentially no further components or no further components are admixed, though.

The aerosol-forming agent can further comprise water. According to certain embodiments, no water is contained, though, since water in aerosol form can burn the mouth of a user. Water can be contained in an amount of 0-15 wt.-% of the total weight percentage of the foam or the aerosol-generating substrate, e.g. 5-10 wt.-%.

EXAMPLES Example 1

The present invention will now be described in detail with reference to examples thereof. However, these examples serve merely as illustrative purpose and do not limit the scope of the invention.

TABLE 1 Tobacco mousse (foam) containing different percentages of carboxylic acid-containing alcohol solution. Tobacco Mousse Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 Propylene glycol  24 wt. %  24 wt. %  24 wt. %  24 wt. %  24 wt. % Glycerin (G)  36 wt.-%  36 wt.-%  36 wt.-%  36 wt.-%  36 wt.-% Stearic acid- and  0 wt.- % 0.2 wt. % 0.5 wt. % 0.8 wt. % 1.0 wt. % decanoic acid- containing alcohol solution Purified Water 3.5 wt.-% 3.5 wt.-% 3.5 wt.-% 3.5 wt.-% 3.5 wt.-% Tobacco Powder 21.5 wt. %  21.3 wt. %  21.0 wt. %  20.7 wt. %  20.5 wt. %  Gum 4.0 wt.-% 4.0 wt.-% 4.0 wt.-% 4.0 wt.-% 4.0 wt.-% Binder  11 wt. % 11.0 wt. %  11.0 wt. %  11.0 wt. %  11.0 wt. %  Total weight 100 wt. %  100 wt. %  100 wt. %  100 wt. %  100 wt. % 

Table 1 shows tobacco mousse (foam) comprising different weight percentages of carboxylic acids (i.e. stearic acid and decanoic acid)-containing alcohol solution were investigated. For producing exemplary foams, the ingredients given in the respective column of Table 1 were mixed and combined as follows.

An equal amount of stearic acid and decanoic acid has been used in all the samples, where these carboxylic acids are dissolved in an alcohol solution. It is believed that due to their chemical similarity, both stearic acid and decanoic acid can be used interchangeably or replaceable. The carboxylic acid-containing alcohol solution has a concentration of 0.1%.

Firstly, the propylene glycol, the glycerin, carboxylic acid alcohol solution (comprising an equal amount of stearic acid and decanoic acid) and optionally the purified water were whipped and aerated for 5-10 min, preferably at 6 min, at 45° C. using a Krups Prep & Cook HP5031 mousse whipping shuffle. When whipping up the mousse, the speed has to be adjusted so that the volume visibly increases, and small bubbles appear and partly stay in the foam. If whipping is too fast then mixing will take over and the foamy structure is going to collapse, thus back to fluid. As one option, whipping is started slowly and the whipping speed is slowly increased as the foam begins to develop a lighter, more mousse-like texture; the speed is backed-off by about 10% if it is noticed that the mousse seems to be reducing its mousse-like texture and becoming seemingly less aerated. In order to preserve the foamy structure for creating the stable portion, a sudden cooling with ice or cool water is recommendable. Using the above mentioned Krups device, the best results can be obtained with a speed in between 60 and 200 rpm. Adaptation is within the skilled person's knowledge in accordance with the above description.

In a next step (within 1 minute of the previous step), the gum was added, and the mixture was whipped and aerated for 5-10 minutes, preferably at 6 min, at 45° C. using a Krups Prep & Cook HP5031 mousse whipping shuffle. Afterwards the tobacco powder was added and whipping, and aeration were carried out for 5-10 min, preferably at 6 min, at 45° C. with the same method. Next, the binder was added, and the mixture was again whipped and aerated for 5-10 min, preferably at 6 min, at 45° C. with the same method. Finally, the mixture was placed in an oven at 50° C. for 12 hours before is ready to be packed and be used.

As no international standard of “sensory evaluation” for a coughing fit is available, the scoring of the “sensory evaluation” for the coughing fit is carried out as described below. Results obtained from the Example 1 were shown in the Table 2.

TABLE 2 Mean coughing fit scores rated by test subjects. Tobacco Mousse (TM) substrate Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 Mean coughing fit score 71.25 36.25 33 39 37

In order to establish a mean coughing fit score, the Sample 1 (containing no carboxylic acid in the consumables) were first given to the test subjects to be rated. Each test subject inhaled 10 puffs within 3 minutes and the degrees of the throat irritation were rated (Score of 100 being very irritated; Score of 60 being rather irritated; Score of 30 being slightly irritated; Score of 0 being not irritated). After Sample 1 being rated, Samples 2, 3, 4 and 5 were given in a random order to the test subjects. The procedure was repeated similar as in the control sample (Sample 1). The coughing fit scores were rated by the test subjects based on their sensation to throat irritation. A pause of 60 seconds (or 120 seconds) is given before a new sample is given to the test subject.

As can be seen in the Table 2, the Samples 2, 3, 4 and 5 which comprised of 0.2 wt.-%, 0.5 wt.-%, 0.8 wt.-% and 1.0 wt.-% of carboxylic acid-containing alcohol solution, respectively, in the total weight percentage mixture of aerosol-generating substrate showed lower mean coughing fit scores compared to the control sample (Sample 1). As an example, the total weight of Sample 1 (0 wt. % Stearic acid and decanoic acid) is 500 g.

Sample 1 (control sample) which did not comprise any carboxylic acid (fatty acid) registered highest mean coughing fit score (71.25). It was observed that aerosol-generating substrates comprising 0.2 wt. % and 1.0 wt. % of carboxylic acid-containing alcohol solution based on the total weight percentage of the aerosol-generating substrates have significantly low scores i.e. less than 40 compared to the control Sample 1, namely 36.25, 33, 39 and 37 for Samples 2, 3, 4 and 5, respectively. These values represent only slightly throat irritation or coughing fit in the Samples 2 to 5 were observed as reported by various test subjects.

Furthermore, in addition to the reduced coughing fit as rated by the test subjects, it was also reported that in samples which comprised of up to 1 wt. % of carboxylic acid-containing alcohol based on the total weight percentage of the aerosol-generating substrate, the taste became smoother and without any negative off-taste, as observed in the Sample 1.

Although the lowest amount of the carboxylic acid-containing alcohol contains in the aerosol-generating substrate performed in the experiment was 0.2 wt. % based on the total weight percentage of the aerosol-generating substrate, it is believe that lower amount such as 0.1 wt. % or 0.05 wt. % based on the total weight percentage of the aerosol-generating substrate would be equally effective in suppressing throat irritation or is has a reduced coughing fit.

To this end, it is reiterated that this surprising effect of the present invention are observed only in any semi-solid substrate (foam, mousse, gel, mucus) and not applicable in solid or liquid medium.

The present foams according to the present invention are not smokable, i.e. are applied in a way that they are not heated to such temperature where they are combusted, but only at least parts thereof are evaporated, particularly at least essentially the aerosol-forming agent and further preferably at least a part of the tobacco-containing agent and/or the inhalable agent. In the present foams, at least some parts of the tobacco-containing agent and/or the inhalable agent preferably is adhered to the foam structure and/or absorbed by the foam structure formed essentially by the foam-forming agent and the foam-stabilizing agent, so that it can be easily released together with the aerosol-forming agent upon heating. Also, it is possible that some parts of the tobacco-containing agent and/or the inhalable agent are bound to the foam structure and the tobacco-containing agent and/or the inhalable agent are “extracted” during heating thereof, so that a flavour from the tobacco-containing agent and/or the inhalable agent is released thereof together with the aerosol-forming agent. According to certain embodiments, the tobacco ingredient containing agent and/or the inhalable agent is configured in such a way that it is released upon heating together with the aerosol-forming agent by only being essentially adsorbed to and/or absorbed in the foam structure. In this regard it was shown by the inventors that a mass loss in the foam can be observed that shows that essentially at least the mass of the foam-forming agent and the foam-stabilizing agent remains. It is assumed that the structure of the foam is mainly formed by the foam-forming agent, which forms a “capsulation” for adhering and/or absorbing the aerosol forming agent and the tobacco ingredient containing agent and/or an inhalable agent, whereas the foam-stabilizing agent stabilizes the foam to keep the foam form. 

1. An aerosol-generating substrate for vaping, comprising a semi-solid substrates, wherein up to about 1.0 wt. % of a total weight percentage of the aerosol-generating substrate is comprised of a carboxylic acid-containing alcohol solution, wherein one or more carboxylic acids are dissolved in the carboxylic acid-containing alcohol solution, wherein the semi-solid substrate is provided in the form of a foam.
 2. The aerosol-generating substrate according to claim 1, wherein the aerosol-generating substrate comprises between 0.2 wt. % and 1 wt. % of the carboxylic acid-containing alcohol solution in the total weight percentage of the aerosol-generating substrate.
 3. The aerosol-generating substrate according to claim 1, wherein the carboxylic acid-containing alcohol solution has a concentration of between about 0.05 v/v % and about 0.2 v/v %.
 4. The aerosol-generating substrate according to claim 1, wherein the one or more carboxylic acids has a hydrocarbon chain length between 9 and 30 carbons.
 5. The aerosol-generating substrate according to claim 1, wherein the one or more carboxylic acids is at least one of Benzoic acid, Levulinic acid, D/L-Tartaric acid, Capric acid, Pyruvic acid, Citric acid, Fumaric acid, D/L-Lactic acid, D/L-Malic acid, Sorbic acid, Adipic acid, L-Aspartic acid, L-Glutamic acid, Succinic acid, Gluconic acid, Linoleic acid, Saccharic acid, 3,7 dimethyl-6-octenoic acid, 2-methyl pentanoic acid, trans-2-Hexenoic acid, Caprylic acid, Lauric acid, Stearic acid, Butyric acid, Linolenic acid, Malonic acid, Myristic acid, Oleic acid, Palmitic acid, Phenylacetic acid, Propionic acid, Valeric acid, Decanoic acid, Hexanoic acid or Octanoic acid.
 6. The aerosol-generating substrate according to claim 1, wherein the carboxylic acid-containing alcohol solution comprises only saturated fatty acid.
 7. The aerosol-generating substrate according to claim 1, wherein the carboxylic acid-containing alcohol solution comprises only stearic acid and decanoic acid.
 8. The aerosol-generating substrate according to claim 1, wherein the carboxylic acid-containing alcohol solution comprises only stearic acid or decanoic acid.
 9. The aerosol-generating substrate according to claim 1, wherein the aerosol-generating substrate further comprises at least one of propylene glycol, 1, 3 propanediol, glycerol, water, gum, flavourant, additives, nicotine, or binder.
 10. (canceled)
 11. An aerosol-generating article comprises the aerosol-generating substrate according to claim
 1. 12. A method of preparing an aerosol-generating substrate for vaping, comprising a semi-solid substrate in the form of a foam, comprising the steps of: a. providing an aerosol-generating substrate comprising at least one of propylene glycol 1, 3-Propanediol, glycerol or water; b. providing one or more carboxylic acids to an alcohol solution, followed by incorporating the one or more carboxylic acids-containing alcohol solution to the aerosol-generating substrate to form a mixture, such that up to about 1 wt. % of a total weight percentage of the aerosol-generating substrate is comprised of the one or more carboxylic acids-containing alcohol solution; and c. constantly mixing the mixture for a certain amount of time, and heating the mixture above room temperature, creating the semi-solid substrate in the form of a foam.
 13. The method according to claim 12, wherein the one or more carboxylic acids-containing alcohol solution has a concentration of between about 0.05 v/v % and about 0.2 v/v %.
 14. The method according to claim 12, wherein the mixture is heated at approximately 45° C. and/or aerated or mixed for approximately 5 minutes.
 15. An aerosol-generating substrate obtainable by the method according to claim
 12. 16. The method according to claim 12, further comprising, after step b, adding at least one of gum, nicotine, flavourant or binder into the mixture.
 17. The aerosol-generating substrate according to claim 1, wherein the aerosol-generating substrate comprises about 0.2 wt. % of the carboxylic acid-containing alcohol solution in the total weight percentage of the aerosol-generating substrate.
 18. The aerosol-generating substrate according to claim 1, wherein the carboxylic acid-containing alcohol solution has a concentration of between about between 0.08 v/v % and 0.15 v/v %.
 19. The aerosol-generating substrate according to claim 1, wherein the carboxylic acid-containing alcohol solution has a concentration of 0.1 v/v %.
 20. The aerosol-generating substrate according to claim 1, wherein the one or more carboxylic acids has a hydrocarbon chain length between 10 and 20 carbons.
 21. The aerosol-generating substrate according to claim 1, wherein the carboxylic acid-containing alcohol solution comprises only stearic acid and decanoic acid in a ratio of 10/90 of stearic acid/decanoic acid. 